I have to evaluate how 4 different environmental variables could be use to explain the variability on the abundance of an specific species of zooplankton. I know that Generalized additive models are useful tools to evaluate this kind of relationships. 1) I want to know the difference to use the "gam" or the "mgvc" package. 2) The model selection is done with the same comands is I use the mgc package? 3) How I evaluate the significance of the smooth and the parametric terms of the model? Thank you, Dacha [[alternative HTML version deleted]]